Frequency resource is limited in a radio communication system. Thus, various techniques have been developed for utilizing the limited frequency resource to a maximum extent. As one of such techniques, a technique is known in which a communication frequency allocated to a radio terminal by a radio base station is dynamically changed in accordance with a radio communication quality of each communication frequency.
In such a technique, the radio terminal measures respective radio communication qualities of a plurality of communication frequencies and notifies the radio base station of radio quality value indicating the measurement result. Based on the radio quality value received from the radio terminal, the radio base station allocates to the radio terminal, a communication frequency with a good radio communication quality from among communication frequencies that can be allocated to the radio terminal. Thus, the radio terminal can perform radio communications with the radio base station using the communication frequency with a good radio communication quality. Accordingly, stable and high-speed radio communications can be achieved.
In LTE (Long Time Evolution), which is a radio communication system standardized in 3GPP (3rd Generation Partnership Project), radio quality value on a predetermined number of communication frequencies with the highest radio communication qualities is notified to the radio base station from the radio terminal (see Non-Patent Document 1).